Video projection systems are widely used in a variety of applications. For example, video projection systems, both forward and rear projection systems, are widely used in “big screen” home entertainment systems to provide a much larger picture than is economically available using a conventional cathode ray tube. Additionally, video projection systems may be used in a theater to display a movie or other video program, or still pictures for a relatively large audience.
Video projection systems are also used in business, education, training and other areas to display presentations such as, pictures, graphs, charts, outlines, etc., for a number of people to view. In one such example, video projection can make it possible for a relatively large number of people to observe a computer desktop and the work being done by an operator of the computer. Because video projection systems are so widely used, there is a constant desire to improve on known video projection systems.
Many such projection systems are now made as portable projector units that can be taken and deployed wherever needed. However, with such a portable projector, it is necessary to focus the projector each time it is deployed in a new environment.
Unfortunately, most people have difficulty focusing a projector, particularly if the image being displayed is a photo image with no clear edges or lines. Some users have to get extremely close to the projected image or display an image with sharp lines or text to be able to accurately focus the projector.